Iran has executed a nuclear scientist who allegedly provided U.S. officials with information about the country's nuclear program.

In 2010, Shahram Amiri returned from the U.S. to Iran, where he was eventually arrested, as NPR's Peter Kenyon told our Newscast unit. "The spokesman for Iran's judiciary tells the official IRNA news agency that Shahram Amiri was executed following his conviction on treason charges," Peter reported.

That spokesman, Gholam-Hossein Mohseni Ejei, said in a news conference that Amiri "had access to top secret information about the Islamic Republic of Iran," which he provided to the United States, according to IRNA.

Amiri's mother told the BBC that "the body had been handed over with rope marks around his neck." This is the first time the Iranian government has acknowledged that "they secretly detained, tried and convicted a man authorities once heralded as a hero," according to The Associated Press.

Big questions remain about how, and why, Amiri disappeared in 2009 and later turned up in the U.S. Correspondent Mike Shuster sketched out the mystery on Morning Edition in 2011:

"Two years ago, Shahram Amiri, a young Iranian nuclear scientist, vanished in Saudi Arabia. For months, nothing was heard of him.

"Then information surfaced that he had defected to the CIA and had provided the United States with crucial information about a secret nuclear site in Iran.

"Last year, Amiri undefected: He surfaced, declaring that he had been a prisoner of the CIA and that he wanted to go home. And so he did. ...

"Amiri was believed to be an agent-in-place for the CIA, who then decided he wanted out of Iran. In the U.S., it appears, he got cold feet and then made his way back to Iran. There he was initially hailed as a hero, but months later he was jailed."

Mike reported that when Amiri returned home in 2010, he said at a news conference that the "CIA drugged and abducted him" and then "used psychological torture to keep him in the U.S." That's a story American officials say is a "fairy tale," Mike added.

According to the AP, U.S. officials said in 2010 that "Amiri was paid $5 million to offer the CIA information about Iran's nuclear program, though he left the country without the money."

Paul Pilar, a former senior CIA official, told Mike that "the Amiri case seems to be a story out of the wilderness of mirrors department — in which intelligence agencies and the services and governments against which they operate are constantly in uncertainty about just where the loyalties of the people they're dealing with ultimately lie."

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